industry-standard single-threaded performance benchmarks absent

By: Jesper Frimann (jesperfrimann.delete@this.gmail.com), February 9, 2010 12:17 pm
Room: Moderated Discussions
Linus Torvalds (torvalds@linux-foundation.org) on 2/9/10 wrote:
---------------------------
>Michael S (already5chosen@yahoo.com) on 2/9/10 wrote:
>>
>>I am not sure that 403.gcc is not broken by autopar.
>
>I'm pretty sure it's not.
>
>See for example
>
>http://hpc.cs.tsinghua.edu.cn/research/cluster/SPEC2006Characterization/auto_para.html
>
>and the spec disclosures I looked at didn't even have
>the -parallel flag. Of course, maybe icc enables autopar
>at O3 even without it, but the manpage says not.
>

It is set with an environment variable, OMP_NUM_THREADS yes a bit sneaky I know.

http://www.spec.org/cpu2006/results/res2010q1/cpu2006-20091214-09270.cfg

int=default=default=default:
sw_compiler000 = Intel C++ Professional Compiler for IA32 and
sw_compiler001 = Intel 64, Version 11.1
sw_compiler002 = Build 20091012 Package ID: l_cproc_p_11.1.059
sw_base_ptrsize = 32-bit
sw_peak_ptrsize = 32/64-bit
notes_000 = OMP_NUM_THREADS set to number of cores
notes_005 = KMP_AFFINITY set to granularity=fine,scatter
sw_other000 = Microquill SmartHeap V8.1
sw_other001 = Binutils 2.18.50.0.7.20080502


And I must admit I do think that 401.gcc benefits from autopar.

If you look at the gains on Nehalem when going from cint to cint rate then
http://www.spec.org/cpu2006/results/res2009q2/cpu2006-20090413-07020.html
with autopar
and
http://www.spec.org/cpu2006/results/res2009q2/cpu2006-20090413-07017.html
with 16 copies.

Then the score only increases a factor of 6.42 going from 'single threaded' to 16 threads. (27,4 -> 176)

If you on the other hand looks at some of the non autopar scores. Lets take POWER just cause that is what we are talking about.

http://www.spec.org/cpu2006/results/res2007q2/cpu2006-20070518-01105.html
Single threaded


http://www.spec.org/cpu2006/results/res2007q2/cpu2006-20070518-01096.html
with 32 copies.

Then you get an increase of a factor 21.7 (19.8 -> 430).

So either Nehalem scales really really badly or the single threaded score is artificially large.
I chose to believe the later.

// Jesper


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TopicPosted ByDate
POWER7 SpecParadox2010/02/08 11:05 AM
  POWER7 SpecThu Nguyen2010/02/08 12:58 PM
    POWER7 SpecIan Ameline2010/02/08 09:22 PM
      POWER7 SpecThu Nguyen2010/02/08 11:54 PM
        POWER7 SpecIan Ameline2010/02/09 06:46 AM
          POWER7 SpecLinus Torvalds2010/02/09 07:57 AM
            industry-standard single-threaded performance benchmarks absentMichael S2010/02/09 08:09 AM
              industry-standard single-threaded performance benchmarks absentParadox2010/02/09 08:33 AM
                industry-standard single-threaded performance benchmarks absentMichael S2010/02/09 09:30 AM
                  industry-standard single-threaded performance benchmarks absentParadox2010/02/09 10:52 AM
                    industry-standard single-threaded performance benchmarks absentJesper Frimann2010/02/09 11:33 AM
              industry-standard single-threaded performance benchmarks absentLinus Torvalds2010/02/09 08:48 AM
                industry-standard single-threaded performance benchmarks absentMichael S2010/02/09 09:26 AM
                  industry-standard single-threaded performance benchmarks absentLinus Torvalds2010/02/09 09:58 AM
                    industry-standard single-threaded performance benchmarks absentJesper Frimann2010/02/09 12:17 PM
                      industry-standard single-threaded performance benchmarks absentLinus Torvalds2010/02/09 12:54 PM
                        industry-standard single-threaded performance benchmarks absentJesper Frimann2010/02/09 02:10 PM
                    industry-standard single-threaded performance benchmarks absentParadox2010/02/09 01:22 PM
                industry-standard single-threaded performance benchmarks absentanon2010/02/09 10:21 AM
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              POWER7 SpecJamie Lucier2010/02/17 10:41 AM
  POWER7 SpecJesper Frimann2010/02/09 04:43 AM
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